JP2008198411A - Manganese dry cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manganese dry cell with excellent corrosion resistance through prevention of leak of electrolyte solution due to a hole on an anode zinc can. <P>SOLUTION: A can of the manganese dry cell is made of an anode zinc can 3, which contains 0.05 to 0.6 wt.% of lead, or is made by molding a zinc plate in a bottomed cylindrical shape in hot impact molding at a temperature in the range of 110 to 130°C, with a crystal particle size of the zinc contained in the anode zinc can 3 of 30 μm or less. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a manganese dry battery including a negative electrode zinc can excellent in corrosion resistance.

  Negative electrode zinc cans used in manganese dry batteries have a problem in that zinc is consumed as the discharge reaction progresses, resulting in a decrease in battery capacity and a decrease in strength. The corrosion resistance of the zinc can was improved by adding. In addition, since the addition of lead imparts ductility to zinc, the workability when forming a zinc plate into a bottomed cylindrical shape has been improved.

  However, at the end of the discharge when the strength of the zinc can decreases, if an impact such as a battery drop is applied or the corrosion of the zinc can progresses excessively due to overdischarge, a hole is opened in a part of the zinc can, and the electrolyte solution May leak outside the battery.

  Conventionally, countermeasures for improving the leakage resistance have been taken against such problems by covering the outer periphery of the negative electrode zinc can with an exterior label. For example, Patent Document 1 describes a technique in which a heat-shrinkable resin film such as polyethylene having excellent electrolytic solution resistance and impact resistance is used for an exterior label.

  However, when an exterior label is used, the outer dimensions of manganese batteries are determined by standards such as JIS, so it is obliged to use a zinc can with a small outer diameter corresponding to the thickness of the exterior label, hindering high capacity. It was a factor.

By the way, considering the corrosion of the negative electrode zinc can in advance, it is possible to improve the leakage resistance of the zinc can without using an exterior label by making the thickness of the negative electrode zinc can thicker than a certain value. is there. For example, as a guideline, prevent the electrolyte from leaking to the outside of the battery by setting the thickness of the negative electrode zinc can so that the ratio of the negative electrode capacitance to the positive electrode capacitance is greater than a certain level. can do.
JP 2006-19091 A

  In order to ensure the leakage resistance of the negative electrode zinc can, the ratio of the negative electrode capacity to the positive electrode capacity (hereinafter simply referred to as “electric capacity ratio”) is set to a certain level (eg, 2.4 or more). Must. In order to satisfy this, the amount of zinc that is the active material of the negative electrode, that is, the thickness of the negative electrode zinc can increases, the internal volume of the battery can decreases accordingly, and the amount of manganese dioxide that is the active material of the positive electrode As a result, the low-rate discharge characteristics are deteriorated. Further, when the electric capacity ratio is increased more than necessary (for example, 4.0 or more), the electric capacity of the positive electrode becomes insufficient with respect to the electric capacity of the excessive negative electrode, and a sufficient discharge capacity cannot be obtained.

  This invention is made | formed in view of this situation, The main objective is to provide the manganese dry battery provided with the negative electrode zinc can excellent in the leakage resistance of electrolyte solution.

  It is considered that the phenomenon that the zinc can finally becomes perforated due to corrosion of the zinc can proceeds in the following reaction form.

  In other words, when the battery is discharged, the reaction starts on the surface of the zinc can, starting from the scratches generated at the time of the can, and the crystal grain boundary of zinc. When used as a lubricant for cans, graphite is one of the reaction starting points). When the reaction proceeds to the inside of the zinc can, only the crystal grain boundary existing inside the zinc can causes the reaction to proceed. That is, as long as there is a crystal grain boundary inside the zinc can, the reaction proceeds along the crystal grain boundary. As a result, it is considered that a hole is formed where the reaction of the zinc can is concentrated.

  Based on such considerations, the inventors of the present application can uniformize the reaction of the zinc can not only on the surface of the zinc can but also inside the zinc can if the crystal grain size of zinc can be made smaller than before. I came up with the idea that the corrosion resistance of zinc cans can be greatly improved.

  By the way, a negative electrode zinc can used for a manganese dry battery is formed by molding a zinc plate obtained by cooling a molten zinc containing lead and rolling it into a plate shape into a bottomed cylindrical shape by impact molding. Conventionally, impact molding (hot impact molding) has been performed by heating a zinc plate to 180 to 200 ° C. in order to achieve a can shape. However, when hot impact molding is performed at such a temperature, recrystallization of zinc proceeds, and the crystal grain size of zinc increases when it is formed. However, from the viewpoint of improving the corrosion resistance of the zinc can, the heating temperature in the hot impact has not been considered at all.

  The manganese dry battery according to the present invention is a manganese dry battery in which the battery can is a negative electrode zinc can, the negative electrode zinc can contains 0.05 to 0.6% by weight of lead, and is included in the negative electrode zinc can. The average crystal grain size of zinc is 30 μm or less.

  Another manganese dry battery according to the present invention is a manganese dry battery in which the battery can is a negative electrode zinc can, and the negative electrode zinc can is bottomed by hot impact molding at a temperature in the range of 110 to 130 ° C. It consists of what was shape | molded by the cylindrical shape, and the crystal grain diameter of the zinc contained in a negative electrode zinc can is 30 micrometers or less, It is characterized by the above-mentioned.

  With such a configuration, the reaction of the zinc can can be made uniform not only on the surface of the zinc can but also on the inside of the zinc can, and the electrolyte leakage due to the perforation of the zinc can is effectively suppressed. Can do.

  Moreover, it is preferable that the electrical capacity ratio of zinc contained in the negative electrode zinc can which is the negative electrode active material to manganese dioxide which is the positive electrode active material is 1.8 or more. Thereby, the thickness of a negative electrode zinc can can be made thinner than before, and the low-rate discharge characteristic of a manganese dry battery can be improved.

  According to the manganese dry battery of the present invention, it is possible to provide a manganese dry battery provided with a negative electrode zinc can excellent in the leakage resistance of the electrolytic solution.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, components having substantially the same function are denoted by the same reference numerals for the sake of simplicity. In addition, this invention is not limited to the following embodiment.

  FIG. 1 is a partial cross-sectional view showing the structure of a manganese dry battery according to an embodiment of the present invention, and the battery can comprises a negative electrode zinc can 3.

  As shown in FIG. 1, a positive electrode mixture 6 containing manganese dioxide, which is a positive electrode active material, is accommodated in a bottomed cylindrical negative electrode zinc can 3 via a separator 7 containing an electrolytic solution. A carbon rod 4 as a current collector is inserted in the center of 6. Further, the upper end opening of the negative electrode zinc can 3 is sealed with the sealing body 2, and the carbon rod 4 penetrates through the center hole of the sealing body 2 and comes into contact with the positive electrode terminal plate 1. 3 is insulated by a bottom paper 8. The outer peripheral surface of the negative electrode zinc can 3 is covered with an exterior label 9.

  The negative electrode zinc can 3 in the present embodiment is one containing 0.05 to 0.6% by weight of lead or a zinc plate into a bottomed cylindrical shape by hot impact molding at a temperature in the range of 110 to 130 ° C. It consists of what was shape | molded and the crystal grain diameter of the zinc contained in the negative electrode zinc can 3 is 30 micrometers or less. Thus, by reducing the crystal grain size of zinc constituting the battery can, the reaction of the zinc can 3 can be made uniform not only on the surface of the zinc can 3 but also inside the zinc can 3. Electrolyte leakage due to the perforation of the can 3 can be effectively suppressed. Thereby, the manganese dry battery excellent in corrosion resistance is realizable.

  Usually, the size of the crystal grains of zinc has a certain distribution (for example, a normal distribution), and the “crystal grain size” means an average crystal grain size. Specifically, the size of each crystal grain present in a certain region is measured, and the average value is defined as “crystal grain size”.

  Moreover, the size of the crystal grains can be measured by various methods. For example, when observed with an optical microscope, a region exhibiting the same color (region of the same reflection surface) or a region closed by a grain boundary is defined as a crystal grain, and the average is obtained by counting the number of crystal grains per fixed line length. The particle diameter is calculated, and the average value obtained for a predetermined number of samples is defined as “crystal grain diameter”. When the crystal grain size is fine, observation with an electron microscope may be used.

  Here, the electric capacity ratio of zinc contained in the negative electrode zinc can 3 as the negative electrode active material to manganese dioxide as the positive electrode active material is preferably 1.8 or more. Since the negative electrode zinc can 3 in the present invention has improved corrosion resistance, the thickness of the negative electrode zinc can 3 can be made thinner than before, and the internal volume of the battery can is increased correspondingly, and is a positive electrode active material. The amount of manganese dioxide can be increased. As a result, the electric capacity ratio that can ensure the liquid leakage resistance of the negative electrode zinc can 3 can be lowered to 1.8, thereby improving the discharge characteristics of the manganese dry battery.

  Moreover, it is preferable that the negative electrode zinc can 3 contains 0.05 to 0.6 weight% of lead at least. In the present invention, since the heating temperature in the hot impact molding is performed at a temperature lower than the conventional temperature, the workability at the time of the can can be maintained by adding lead to the zinc can 3.

  As manganese dioxide, it is preferable to use electrolytic manganese dioxide that can provide a high discharge capacity, but in consideration of manufacturing costs, inexpensive natural manganese dioxide or chemical manganese may be used. The separator 7 may be, for example, a paste obtained by applying a paste obtained by dissolving a cross-linked starch and a binder mainly composed of vinyl acetate in an alcohol solvent on one side of kraft paper. For the sealing body 2, for example, a polyolefin resin such as polyethylene or polypropylene, or nylon can be used. The sealing body 2 is fastened by the outer peripheral edge portion of the positive electrode terminal plate 1 fitted to the top of the carbon rod 4 and the caulking portion of the open end portion of the negative electrode zinc can 3. The exterior label 9 may be a heat-shrinkable resin film such as polyethylene, polyvinyl chloride, polystyrene, or polyethylene terephthalate.

  Hereinafter, based on an Example, the result of having evaluated the corrosion resistance of the manganese dry battery concerning this invention is demonstrated. In addition, this invention is not limited to a following example.

(Preparation of negative electrode zinc can)
After melting 99.99% purity zinc at about 500 ° C. using a melting furnace, lead corresponding to 0.15% by weight of zinc was added to obtain a molten zinc alloy. Thereafter, the molten zinc alloy was cooled to a plate shape having a thickness of 10 mm, and punched out by a press to obtain a button-shaped piece having a diameter of 12.8 mm and a height of 4.5 mm. A lubricant composed of talc, zinc stearate, and boric acid in a weight ratio of 3: 1: 1 was fixed to the surface of the small piece.

  This small piece is used as a base material, heated in advance to a predetermined temperature (hereinafter referred to as “preheating temperature”), and then subjected to hot impact molding to have an outer diameter of φ13.6 mm, a side thickness of 0.25 mm, and a bottom thickness. A negative electrode zinc can 3 of a bottomed cylindrical AA manganese dry battery having a thickness of 0.4 mm was obtained. This negative electrode zinc can 3 had a zinc content of 99.7% by weight and contained 0.15% by weight of lead with respect to zinc.

(Manufacture of manganese batteries)
Using the negative electrode zinc can 3 obtained above, the AA manganese dry battery shown in FIG. 1 was produced. Here, electrolytic manganese dioxide having a purity of 91% was used for manganese dioxide, and acetylene black was used for carbon powder. Further, as the electrolytic solution, an aqueous solution containing 2% by weight of ammonium chloride and 30% by weight of zinc chloride was used. And the positive electrode mixture 6 which mixed manganese dioxide, carbon powder, and electrolyte solution by the weight ratio of 5: 1: 4.4 is filled through the separator 7 in the negative electrode zinc can 3, Furthermore, the negative electrode zinc can Was covered with an exterior label 9 to produce manganese dry batteries 1-9. In addition, all the electric capacity ratios of the manganese dry battery were 1.98.

  Table 1 shows the size of the average crystal grain size of zinc in the negative electrode zinc can in each manganese dry battery when the negative electrode zinc can 3 formed at different preheating temperatures was used, and the leakage test. This shows the results.

  Here, the average crystal grain size of the negative electrode zinc can 3 was calculated by taking an enlarged photograph of the sample cut out from the negative electrode zinc can 3 and counting the number of crystal grains per certain line length. In addition, the leakage test was performed by loading 100 manganese batteries into 5 commercially available flashlights (using 2 AA batteries), lighting them for 30 minutes per day, and repeating this every day. When the lighting could not be performed, each battery was taken out and the number of leaked batteries was counted.

  As shown in Table 1, in manganese dry batteries 7 to 9 manufactured using negative electrode zinc cans (average crystal particle diameter of 30 μm or less) formed with a preheating temperature of hot impact in the range of 110 to 130 ° C., leakage occurred. No liquid was produced. It can also be seen that when the preheating temperature is 140 ° C. or higher, the number of liquid leaks increases as the average crystal particle diameter increases. From this result, the leakage of electrolyte can be effectively suppressed by reducing the crystal grain size of zinc and making the reaction of the zinc can uniform not only on the surface of the zinc can but also inside the zinc can. I understand. Note that if the preheating temperature is set to 110 ° C. or less, the crystal grain size can be further reduced, but conversely, the heating in the hot impact molding becomes insufficient and there is a problem that it becomes difficult to obtain a negative electrode zinc can having a uniform shape. is there. Accordingly, the preheating temperature is preferably in the range of 110 to 130 ° C.

  Next, as a result of evaluating the relationship between the electrical capacity ratio of zinc (negative electrode active material) to manganese dioxide (positive electrode active material) and leakage resistance of the manganese dry battery when the corrosion resistance of the manganese dry battery is improved according to the present invention. Will be explained.

(Production of manganese batteries with different electric capacity ratios)
The negative electrode zinc can 3 used was formed by hot impact molding at a preheating temperature of 130 ° C. (average crystal particle diameter was 30 μm). The outer diameter (φ) of the negative electrode zinc can 3 was 13.6 mm, the side surface thickness (t) was 0.25 mm, and the bottom surface thickness was 0.4 mm. The zinc content was 99.7% by weight, and the lead content relative to zinc was 0.15% by weight.

And the manganese dry batteries 10-17 from which the magnitude | size of a positive electrode electric capacitance differs were produced by changing the weight ratio of the manganese dioxide with respect to the carbon powder of the positive electrode mixture 6. FIG. The negative electrode capacitance (C ₁ : constant) and the positive electrode capacitance (C ₂ ) were calculated using the following formulas (1) and (2), respectively.
C ₁ = [(φ / 2) ² − (φ / 2−t) ² ] × π × H × ρ × P _Zn × C _Zn (1)
Where φ is the outer diameter of the zinc can, t is the thickness of the side surface of the zinc can, H is the height of the zinc can, ρ is the density of zinc, P _Zn is the zinc content, and C _Zn is the theoretical electricity of zinc. Capacity (0.820 Ah / g).
C ₂ = M × P _Mn × P _Mn × C _Mn (2)
Here, M weight of the positive electrode _mixture, the _{P Mn} is the content of manganese _{dioxide, P Mn} purity of manganese _{dioxide, C Mn} theoretical electric capacity of the manganese dioxide (0.308Ah / g).

Table 2 shows the leakage test (Evaluation 1) in each manganese dry battery and the leakage test (evaluation) during overdischarge when producing the manganese dry batteries 10 to 17 having different capacitance ratios (C ₁ / C ₂ ). It is the table | surface which showed the result of 2).

  Here, in the overdischarge leakage test, 100 manganese batteries were loaded into 5 commercially available flashlights (using 2 AA batteries) and turned on without turning off the lights. This was carried out by leaving it for one month and then taking out each battery and counting the number of leaked batteries.

  As shown in Table 2, in the leak test (Evaluation 1) of the same method as in Table 1, no leak occurred in all the manganese dry batteries 10-17. On the other hand, in the overdischarge leakage test (Evaluation 2), no leakage occurred in the manganese dry batteries 10 to 14 having an electric capacity ratio of 1.8 or more. That is, the negative electrode zinc can formed by hot impact molding at a preheating temperature of 130 ° C. is excellent in corrosion resistance, so that even if the amount of manganese dioxide is increased (electric capacity ratio is reduced), overdischarge Leakage due to can be prevented. Thereby, the low-rate discharge characteristic of a manganese dry battery can be improved.

  As mentioned above, although this invention was demonstrated by suitable embodiment, such description is not a limitation matter and of course various modifications are possible. For example, in the above embodiment, the negative electrode zinc can was formed by hot impact molding at a temperature in the range of 110 to 130 ° C., but instead of hot impact molding, the negative electrode zinc can was formed by drawing. Can be grown. Although this drawing process is inferior in productivity to hot impact molding, it does not require heating in the process of forming the negative electrode zinc can, so the recrystallization of zinc hardly progresses and the crystal grain size of 5 μm or less Thus, the corrosion resistance of the negative electrode zinc can can be improved.

  The manganese dry battery according to the present invention is excellent in the leakage resistance of the electrolyte, and is useful as a power source for flashlights, portable electronic devices, and the like.

It is the fragmentary sectional view which showed the structure of the manganese dry battery in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode terminal board 2 Sealing body 3 Negative electrode zinc can 4 Carbon rod 6 Positive electrode mixture 7 Separator 8 Bottom paper 9 Exterior label

Claims (9)

The battery can is a manganese dry battery made of a negative electrode zinc can,
The said negative electrode zinc can contains 0.05 to 0.6 weight% of lead, and the average crystal grain diameter of the zinc contained in the said negative electrode zinc can is 30 micrometers or less. The battery can is a manganese dry battery made of a negative electrode zinc can,
The negative electrode zinc can consists of a zinc plate formed into a bottomed cylindrical shape by hot impact molding at a temperature in the range of 110 to 130 ° C.
A manganese dry battery, wherein an average crystal grain size of zinc contained in the negative electrode zinc can is 30 μm or less.   The manganese dry battery of Claim 1 or 2 whose electric capacity ratio of zinc contained in the said negative electrode zinc can which is a negative electrode active material with respect to manganese dioxide which is a positive electrode active material is 1.8 or more.   The manganese dry battery according to claim 3, wherein an electric capacity ratio of zinc contained in the negative electrode zinc can, which is a negative electrode active material, to manganese dioxide, which is a positive electrode active material, is 4.0 or less.   The manganese dry battery according to claim 1 or 2, wherein an outer peripheral surface of the negative electrode zinc can is covered with an exterior label. The battery can is a manganese dry battery made of a negative electrode zinc can,
The negative electrode zinc can consists of one formed into a bottomed cylindrical shape by drawing without heating the zinc plate,
A manganese dry battery, wherein the negative electrode zinc can has a crystal particle size of 5 μm or less.   The manganese dry battery according to claim 6, wherein an electric capacity ratio of zinc contained in the negative electrode zinc can, which is a negative electrode active material, to manganese dioxide, which is a positive electrode active material, is 1.8 or more.   The manganese dry battery according to claim 7, wherein an electric capacity ratio of zinc contained in the negative electrode zinc can, which is a negative electrode active material, to manganese dioxide, which is a positive electrode active material, is 4.0 or less.   The manganese dry battery according to claim 6, wherein an outer peripheral surface of the negative electrode zinc can is covered with an exterior label.

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